Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io

Vishal Verma
2016-04-26T15:01:53Z

On Tue, 2016-04-26 at 01:33 -0700, hch@infradead.org wrote:
> On Mon, Apr 25, 2016 at 05:14:36PM +0000, Verma, Vishal L wrote:
> >
> > - Application hits EIO doing dax_IO or load/store io
> >
> > - It checks badblocks and discovers it's files have lost data
> >
> > - It write()s those sectors (possibly converted to file offsets
> > using
> > fiemap)
> > ?? ?? * This triggers the fallback path, but if the application is
> > doing
> > this level of recovery, it will know the sector is bad, and write
> > the
> > entire sector
> This sounds like a mess.
>
> >
> > I think if we want to keep allowing arbitrary alignments for the
> > dax_do_io path, we'd need:
> > 1. To represent badblocks at a finer granularity (likely cache
> > lines)
> > 2. To allow the driver to do IO to a *block device* at sub-sector
> > granularity
> It's not a block device if it supports DAX.  It's byte addressable
> memory masquerading as a block device.

Yes but we made that decision a while back with pmem :)
Are you saying it should stop being a block device anymore?

> --
> To unsubscribe from this list: send the line "unsubscribe linux-
> block" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html